Sn0wbreeze 2.2 is out! Just like PwnageTool for Mac, you can now cook custom firmwares of iOS 4.2.1 on Windows without upgrading the baseband, which ultimately means that you can use ultrasn0w unlock software to unlock your phone on the older baseband.
Sn0wbreeze: http://ih8sn0w.com/index.php/download/f ... reeze22/pc
IOS 4.2.1: viewtopic.php?p=509542#p509542
Sn0wbreeze 2.2 supports all iDevices including the Apple TV !
Instructions are as follows:
Step 1: Download and install the latest version of iTunes.
Step 2: Now start iTunes and sync your iPhone with your PC so that it backs-up all your important data including settings, apps, music, contacts and photos.
Step 3: Download Sn0wbreeze 2.2 and the original iOS 4.2.1 firmware file for your version of iPhone or iPod touch. Move all these files to your desktop.
Step 4: Start Sn0wbreeze and select “Expert Mode”.
Step 5: Sn0wbreeze will now ask you to browse for your .ipsw file. Select the correct iOS 4.2.1 firmware .ipsw file by clicking the “Browse” button. Sn0wbreeze will verify the selected file and then will present you with following screens.
Also check “Activate The iPhone” if you are on unofficial carrier and want Sn0wbreeze to hacktivate your phone.
Step 7: Now simply select “Build IPSW”. Sn0wbreeze will now create the custom .ipsw file for your iPhone which will be jailbroken.
Step 8: Now you will have to restore your iPhone to this custom firmware 4.1 that you just cooked using Sn0wbreeze for your iPhone. Click on your phone from the sidebar in iTunes and then press and hold left “Shift” button on the keyboard and then click on “Restore” (Not “Update” or “Check for Update”) button in the iTunes and then release the “Shift” button.
This will make iTunes prompt you to select the location for your custom firmware 4.1. Select that custom .ipsw file and click on “Open”.
Step 9: Now sit back and enjoy as iTunes does the rest for you. This will involve a series of automated steps. Be patient at this stage and don’t do anything silly. Just wait while iTunes installs the new iOS 4.2.1 on your iPhone. Your iPhone screen at this point will be showing a progress bar indicating installation progress. After the installation is done, iPhone will restart automatically and you should now have a fully jailbroken iPhone running on iOS 4.2.1
How to: Unlock iOS 4.2.1 (Old Baseband):
Once you are done with the jailbreak, you can follow our step by step guide posted here
to unlock your iPhone on iOS 4.x, on older baseband using Ultrasn0w.
Step 10: Once you are done with the unlocking and jailbreak process. You can now restore all your settings, apps, music, contacts and photos to the newly installed iOS 4.2.1 by restoring the backup that you made in Step 2 from iTunes.
Feel free to ask me any question here should you run into any problem during the jailbreak process.